<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div class="remClass">rem测试字体</div>
    <style>
        html{
            font-size: 14px;
        }
        @media screen and (max-width: 1450px){
            html{
                font-size: 12px;
            }
        }
        .remClass{
            font-size: 2rem; 
            background: red;
            height: 4rem;
            width: 20rem;
        }
    </style>
</body>
</html>